The California Department of Food and Agriculture's preliminary figures show that the crop of red and white varieties combined weighed in at 4.23 million tons in 2013, up 5 percent from 4.02 million tons in 2012.

The industry is well positioned to take advantage of the large crops, said Heidi Scheid, chairwoman of the winegrape growers' association.

"After short crops in 2010 and 2011, growers delivered two remarkable vintages, with record-sized harvests and exceptional quality," she said.

While Napa County's vineyards carry international cache, the San Joaquin Valley, stretching for 220 miles from Stockton to Bakersfield, is the U.S.'s most prolific grape-growing region and home to 44 percent of the state's crop.

Along with raisins and table grapes, vast tracts of wine grapes are mechanically harvested for popular labels such as Gallo's economy brands and Bronco's popular Charles Shaw, aka Two Buck Chuck, and blended into higher end wines.

Large growers in the valley are poised to profit from the higher volumes, analysts said.

"We had a good-quality harvest, and heavier than expected," Fred Franzia, CEO of Bronco, said in an email. Bronco is California's largest vineyard owner.